Resins which have been rendered reactive have been used in various fields. Ethylenically unsaturated group-containing isocyanate compounds are useful for the production of such resins. For example, an ethylenically unsaturated group or isocyanate group can be introduced into the resin through a reaction with a functional group in the main chain of the resin.
On the other hand, functions such as high curing speed and high crosslinking density in cured products obtained therefrom are required of resins and resin compositions. To impart such functions, ethylenically unsaturated group-containing isocyanate compounds capable of introducing a plurality of ethylenically unsaturated groups into resin molecules and a process for producing the same have been desired. Further, for applications and fields where such compounds are used, typified by optical materials, polyelectrolytes and the like, such compounds should have high purity.
Regarding the production of such ethylenically unsaturated group-containing isocyanate compounds, for example, patent document 1 discloses the following two production processes. The first process comprises reacting an amino alcohol with ethyl chlorocarbonate to give ethyl hydroxycarbamate, then reacting this compound with an unsaturated carboxylic acid chloride to give an urethanoester, and then thermally decomposing the urethanoester in the presence of phosphorus pentachloride or the like to give an unsaturated carboxylic acid isocyanatoalkyl ester.
The second process comprises preparing a chloroalkyl ester by transesterification from a methyl ester of an unsaturated carboxylic acid and chloroalcohol, then reacting this compound with an alkali metal isocyanate and ethanol to give an urethanoester of an unsaturated carboxylic acid, and then thermally decomposing this compound in the presence of phosphorus pentachloride or the like to give an isocyanatoalkyl ester of an unsaturated carboxylic acid.
These processes, however, suffer from a problem that phosphorus and sulfur are present as impurities. Further, the resultant product contains a large amount of by-products which appear to derive from the unsaturated group (for example, HCl adduct of unsaturated group). Therefore, these processes involve problems such as very low reaction yield and the necessity of a large amount of labor for purification.
Patent document 2 discloses a process which comprises reacting an unsaturated carboxylic acid chloride with an amino alcohol hydrochloride to synthesize an aminoalkyl ester hydrochloride of an unsaturated carboxylic acid and then reacting this compound with carbonyl chloride to give an isocyanatoalkyl ester of an unsaturated carboxylic acid.
Patent document 3 discloses a process which comprises reacting an imidazole derivative with carbonyl chloride, reacting the resultant compound with a monoalkanolamine, and then esterifying the resultant compound using an unsaturated carboxylic acid or its chloride or ester to give an isocyanatoalkyl ester of an unsaturated carboxylic acid.
Also in these processes disclosed in patent documents 2 and 3, however, the resultant compounds contain a large amount of by-products which appear to derive from the unsaturated group (for example, HCl adduct of the unsaturated group), posing problems such as low reaction yield and the necessity of a large amount of labor for purification.
Patent document 4 and patent document 5 disclose a process in which a 2-alkenyl-2-oxazoline is reacted with phosgene to give an isocyanatoalkyl ester of an unsaturated carboxylic acid. This process is very advantageous from the viewpoints of energy saving and safety and has been carried out on a commercial scale. Furthermore, patent document 6 to patent document 9 propose production processes of 2-alkenyl-2-oxazolines as a precursor compound.
In these processes, however, expensive oxazoline compounds are used as a starting compound, and, in addition, the process is long. Therefore, these processes are cost-ineffective. Further, since a large amount of HCl adducts of the unsaturated group are contained as by-products, disadvantageously, for example, a large amount of labor is required for purification.
Further, patent document 10 discloses a process which comprises reacting dimethyl carbonate, diethyl carbonate, or dipropyl carbonate with ethanolamine to synthesize hydroxy urethane, reacting this compound with an unsaturated carboxylic acid or its chloride or ester to give a urethanoester, and thermally decomposing this compound to give an isocyanatoalkyl ester of an unsaturated carboxylic acid.
In this process, the thermal decomposition of the urethanoester is difficult, and the percentage decomposition is 50% to 60%, for example, even at a high temperature of 400° C. The unsaturated carboxylic acid isocyanatoalkyl ester contains an ethylenically unsaturated group and thus is polymerized at this high temperature, leading to problems of lowered yield and safety problems such as clogging of the thermal decomposition reactor. Therefore, the practice of this process on a commercial scale is considered difficult.
Further, conventional processes are also disadvantageous in that a large amount of by-produced chlorine compounds and the like stay in the reaction solvent. This is considered to affect, for example, the stability of the contemplated compound at the time of purification. Further, in the prior art documents, there is no description on a technique about a compound containing in its molecule two or more polymerizable functional groups, that is, two or more ethylenically unsaturated groups, and, at the same time, containing an isocyanate group.
On the other hand, monomers, oligomers or polymers containing a urethane bond with a reactive ethylenically unsaturated group-containing isocyanate compound added thereto have hitherto been used in various fields such as coating materials, UV- and heat-curable coating materials, molding materials, adhesives, inks, resists, optical materials, stereolithographic materials, printing plate materials, dental materials, polymer battery materials, and starting materials for polymers. For example, applications of optical materials include optical lenses, films, materials for optical antireflection films such as glass for CRTs, materials for cladding materials for optical fibers, or optical adhesives, for example, for optical fibers and optical lenses.
Urea bond-containing monomers, oligomers, or polymers to which a reactive ethylenically unsaturated group-containing isocyanate compound was added have also been used in the same applications.
Regarding compositions used in optical lenses, comprising a urethane bond-containing compound, patent document 12 discloses a curable composition comprising a compound produced by reacting a diol such as a cycloolefin diol with 2-methacryloyloxyethyl isocyanate.
Patent document 21 discloses a curable composition comprising urethane(meth)acrylate produced by reacting a bisphenol-type diol with a polyisocyanate and a hydroxy-containing (meth)acrylate. In the technique disclosed in this document, an aromatic ring or cycloolefin ring has been introduced to enhance the refractive index or transparency of the lens.
This, however, increases the rigidity of the polymer and, thus the adhesion to a mold base material for providing dimensional accuracy is lowered. Further, upon curing, the crystalline area is increased, leading to lowered transparency.
In patent document 13, a fluorine-containing composition comprising a compound produced by reacting a carboxyl-containing ethylenically unsaturated monomer with a copolymer of a fluoroethylenically unsaturated monomer and glycidyl acrylate is disclosed as a fluorine-containing fluoroethylenically unsaturated compound which is a low-refractive index materials used, for example, in materials for antireflection films, materials for cladding of optical fibers, and optical adhesives.
In patent document 14, a photocurable composition comprising a (meth)acrylate compound containing in its structure a urethane bond-containing fluorine-containing monofunctional(meth)acrylate and a fluorinated polyether is disclosed as a urethane bond-containing polymer or monomer. Patent document 15 discloses a specific fluorine-containing ethylenically unsaturated compound produced by reacting a fluorohydroxy compound with a monofunctional (meth)acrylate group-containing isocyanate compound.
In patent document 13, the reactivity and the adhesion to base materials are enhanced by introducing a reactive group into a polymer side chain by a glycidyl group. In patent document 14, a photocurable composition comprising a fluorine-containing urethane(meth)acrylate and a fluorine-containing polyether realizes a highly transparent, low-refractive index ultraviolet-curable composition. They, however, are monofunctional monomers and suffer from problems of curability and adhesion. Further, crystallization upon curing causes a problem of opacity.
In patent document 15, a fluorine-containing hydroxyl compound is reacted with acrylic acid and a monofunctional (meth)acrylate group-containing isocyanate compound for conversion to a polyfunctional monomer, whereby the reactivity is enhanced and, at the same time, compatibility with other monomer is improved. This technique, however, is disadvantageous, for example, in that the fluorine content is low and a further increase in fluorine content causes a lowering in curability.
In the techniques disclosed in the above patent documents, for the reason that the fluorine content affects the refractive index, transparency, adhesion, heat resistance or the like, a curing composition is produced by mixing or reacting a fluoroethylenically unsaturated monomer with other polymer, particularly a fluoropolymer. However, problems of curability and adhesion remain unsolved. Further, upon curing, a crystalline region is formed, resulting in clouding.
Furthermore, in patent document 16, a polyfunctional urethane acrylate produced by adding a diisocyanate to a bisphenol-type acrylate is disclosed as hardcoat materials for use in the protection of the surface of glass base materials for various displays or the like, or plastic base materials. Patent document 17 discloses a curable composition comprising a urethane acrylate compound produced by reacting a polyester polyol or a polycarbonate polyol with a polyisocyanate and a hydroxyl-containing (meth)acrylate.
In the techniques disclosed in patent document 16 and patent document 17, curability, adhesion and surface hardness are provided by adding a monofunctional isocyanate to a polyol.
Regarding a urethane bond-containing compound, in patent document 18, a photocurable composition comprising an ethylenically unsaturated group-containing oligomer in which bonding has been achieved through a urea bond, and a specific photopolymerization initiator is disclosed as a coating material for optical fibers, which contributes to an improvement in photocurability and heat resistance of the overcoat. In order to enhance the curability and heat resistance, however, specific photopolymerization initiator and composition are required.
In patent document 19, a thermally polymerized material produced by allowing an isocyanate-terminated prepolymer, obtained by reacting an aliphatic diisocyanate with a diol, to react with an aromatic diamine is disclosed as a transparent material suitable for optical applications. In this technique, the transparency and heat resistance are improved by producing a cured product through a reaction between an isocyante group and an amine group.
Patent document 20 discloses a thiourethane having a specific structure formed from an isocyanate group and a thiol compound.
In these prior art techniques as well, however, regarding urethane bond-, urea bond-, or thiourethane bond-containing reactive monomers, oligomers, or polymers for use in optical applications or other fields, problems of curability, adhesion to base materials, transparency, and heat resistance remain unsolved, and any satisfactory material has not been developed.
Monomers, oligomers or polymers containing a urethane bond with the reactive ethylenically unsaturated group-containing isocyanate compound added thereto have hitherto been used in various fields. As a result of detailed review of these prior art techniques, it has been found that, for the field of resist materials, the reactive polymer has the following problems in the field of photosensitive compositions for color filters used in the production of color filters for LCDs. In conventional color filters, a black matrix (K) is formed on a surface of transparent substrate such as glass or a plastic sheet. Subsequently, three or more different hues such as red (R), green (G), and blue (B) are formed successively in a color pattern such as a stripe or mosaic form. The black matrix is disposed in a lattice, stripe or mosaic form between R, G, and B color patterns and functions to suppress color mixing between colors for a contrast improvement or to prevent light leakage-derived malfunction of a thin film transistor (TFT).
Therefore, a high level of light shielding properties are required of the black matrix, and, as disclosed in patent document 22, for example, a method in which the content of light shielding pigments or dyes is increased has been studied. This method, however, suffers from a problem that the sensitivity, developability, resolution, adhesion and the like of the photosensitive composition are deteriorated. Accordingly, the productivity is lowered, and, in addition, the accuracy and reliability required of the color filter cannot be provided. That is, the development of a curable composition which can exhibit good sensitivity (curability), adhesion, developability, and resolution under thin film and high light shielding conditions has been desired.
On the other hand, the same problems are involved in the field of solder resists used in printed wiring boards. Solder resists are used to protect a wiring (circuit) pattern on a substrate against an external environment and to coat a protective layer called a cover coat or a solder mask onto a printed wiring board from the viewpoint of preventing solder from being deposited onto an unnecessary part in the step of soldering in mounting an electronic component on a surface of a printed wiring board.
As disclosed in patent document 23, a polyfuntional epoxy resin system has been mainly used. In this case, the resultant cured film has good heat resistance, but on the other hand, the flexibility is disadvantageously low. Accordingly, the application of the above solder resist is limited to a rigid plate where the flexibility is not required of the cured film, and the use of the cured film in flexible printed wiring boards (FPCs) which have become more and more used in recent years is difficult.
Under these circumstances, in recent years, a number of proposals have been proposed on flexible solder resists. For example, patent document 24 discloses a composition comprising a carboxyl-containing urethane(meth)acrylate compound. The technique disclosed in this patent document 24 can improve flexibility, but on the other hand, due to great influence of crosslinkability and adhesion of the polymer, the chemical resistance, particularly gold plating resistance, is unsatisfactory.
The above properties of the photosensitive composition are mainly derived from the polymer used, and, thus, the structure of the polymer should be improved.    [Patent document 1] U.S. Pat. No. 2,718,516    [Patent document 2] U.S. Pat. No. 2,821,544    [Patent document 3] Japanese Patent Laid-Open No. 129163/1990    [Patent document 4] U.K. Patent No. 1,252,099    [Patent document 5] Japanese Patent Laid-Open No. 010750/1988    [Patent document 6] Japanese Patent Laid-Open No. 010771/1988    [Patent document 7] Japanese Patent Laid-Open No. 010772/1988    [Patent document 8] Japanese Patent Laid-Open No. 010773/1988    [Patent document 9] Japanese Patent Laid-Open No. 010774/1988    [Patent document 10] Japanese Patent Laid-Open No. 195354/1987    [Patent Document 11] Japanese Patent Laid-Open No. 143220/1997    [Patent Document 12] Japanese Patent Laid-Open No. 104401/1998    [Patent Document 13] Japanese Patent Laid-Open No. 14221/1989    [Patent Document 14] Japanese Patent Laid-Open No. 43671/2004    [Patent Document 15] Japanese Patent Laid-Open No. 48856/2001    [Patent Document 16] Japanese Patent Laid-Open No. 296152/1997    [Patent Document 17] Japanese Patent Laid-Open No. 287718/1998    [Patent Document 18] Japanese Patent Laid-Open No. 200007/2001    [Patent Document 19] Japanese Patent Laid-Open No. 226806/2003    [Patent Document 20] Japanese Patent Laid-Open No. 104842/2005    [Patent Document 21] Japanese Patent Laid-Open No. 333902/2004    [Patent document 22] Japanese Patent Laid-Open No. 300923/1998    [Patent document 23] Japanese Patent Laid-Open No. 228688/1999    [Patent document 24] Japanese Patent Laid-Open No. 229201/2002